1. Field of the Invention
The present invention relates to an electronic component to be used for various electronic apparatuses and a method of manufacturing the same, and more particularly to an electronic component such as a capacitor or a battery which has an electrochemical element winding an electrode foil that connects a leading terminal thereto.
2. Description of the Related Art
In recent years, with digitization of electronic apparatus, it has been demanded to reduce size, to increase capacity and to reduce equivalent series resistance (hereinafter referred to as ESR) in electronic components to be used in circuits for power output/input, for example, a smoothing circuit or a control circuit.
With reference to FIGS. 8 and 9, description will be given of an electrolytic capacitor according to an example of a conventional electronic component. FIG. 8 is a developed perspective view showing a capacitor element of the conventional electrolytic capacitor. FIG. 9 is a sectional view showing the conventional electrolytic capacitor.
As shown in FIG. 9, the electrolytic capacitor has capacitor element 3 constituting an electrochemical element, an electrolytic solution (not shown) constituting an electrolyte, and outer housing 11 for accommodating capacitor element 3 and the electrolytic solution. Ends 1a and 2a of leading terminals 1 and 2 are connected to capacitor element 3 respectively, and furthermore, other ends 1b and 2b of leading terminals 1 and 2 are led to an outside of outer housing 11. Capacitor element 3 is accommodated in outer housing 11 in order to lead each of other ends 1b and 2b of leading terminals 1 and 2 to the outside.
Outer housing 11 is constituted by outer case 12 and sealing member 13. Outer case 12 is formed of a metal and accommodates capacitor element 3 impregnated with the electrolytic solution. Sealing member 13 has through holes 13a and 13b for inserting leading terminals 1 and 2 therethrough, respectively. Sealing member 13 is disposed in an opening part of outer case 12, and an outer peripheral surface of outer case 12 is narrowed down to form throttling portion 12a so that the opening portion of outer case 12 is sealed. Rubber packing is used for sealing member 13.
Moreover, capacitor element 3 is formed by winding anode foil 4 and cathode foil 5 with insulating separator 6 provided therebetween as shown in FIG. 8. Anode foil 4 is formed by roughening a foil formed of a valve metal such as aluminum through an etching treatment, and furthermore, forming an anodic oxide film (not shown) on a surface of the foil carrying out a chemical conversion treatment. Cathode foil 5 is formed of a valve metal such as aluminum. Ends 1a and 2a are connected to anode foil 4 and cathode foil 5 at connecting portions 1d and 2d, respectively. Ends 1b and 2b are led out of an end face of capacitor element 3 formed by winding anode foil 4, cathode foil 5 and separator 6.
Insulating members 7 and 8 are stuck to separators 6 in order to coat positions corresponding to ends 1a and 2a with separators 6, respectively. In some cases, insulating members 7 and 8 are directly stuck and fixed to anode foil 4 and cathode foil 5 in order to directly cover ends 1a and 2a connected to anode foil 4 and cathode foil 5.
In an electrolytic capacitor, generally, separator 6 provided between anode foil 4 and cathode foil 5 is reduced in a thickness and a density in order to decrease the ESR. In that case, there is a fear that a burr generated in formation of ends 1a and 2a or a burr of connecting portions 1d and 2d at which ends 1a and 2a are connected might break through separator 6, resulting in an increase in generation of short circuits. On the other hand, referring to the electrolytic capacitor according to the related art, insulating members 7 and 8 are stuck to separator 6 placed in the corresponding positions to ends 1a and 2a which is a main factor for the generation of the short circuits. Consequently, low ESR can be implemented, and at the same time, short-circuit resistance can be improved so that reliability can be enhanced.
As prior art documents related to the invention of the present application, for example, there are known Unexamined Japanese Patent Publication No. 2006-286959 and Unexamined Japanese Patent Publication No. H06-45202.
In order to prevent contact of other end 1b of leading terminal 1 led from the end face of capacitor element 3 formed by the winding and cathode foil 5, contact of other end 2b of leading terminal 2 and anode foil 4, and contact of metallic outer case 12 and anode foil 4, an end of insulating separator 6 is protruded from the end face most greatly. For this reason, insulating members 7 and 8 cannot be recognized visually. Accordingly, it is impossible to decide whether insulating members 7 and 8 are normally attached or not and whether they are disposed in predetermined positions or not after fabrication of capacitor element 3. In other words, there might be generated a defective product in which insulating members 7 and 8 are not normally attached to the inner part of capacitor element 3 or they are abnormally disposed even if they are attached after capacitor element 3 is fabricated. If the defective product of capacitor element 3 is not eliminated but flows out, there is a fear that short-circuit resistance cannot be ensured stably in an electrolytic capacitor using capacitor element 3.